Hover aircraft are commonly employed when maneuvering close to fixed and/or moving obstacles, as for example when taking off and/or landing on a ship, or carrying out rescue or salvage operations in emergency situations and/or poor-access locations, such as mountain or sea rescue operations.
In such cases, an operator visually ensures the aircraft stays a given distance from the obstacle.
If the aircraft comes too close to the obstacle, thus risking collision between the blades of one of the rotors and the obstacle, the operator alerts the pilot who accordingly pulls the aircraft back.
A need is felt within the industry to safeguard against collision between the aircraft and the obstacle caused by judgment errors on the part of the operator and/or errors in communication between the operator and pilot.
U.S. Pat. No. 5,371,581 discloses an aircraft provided with a sensor which has a quasi-horizontal sweep region and designed to acquire values of distances between points of an obstacle within the sweep region and a point of the aircraft. In detail, the sensor comprises a rotating optics which protrudes from the bottom portion of the fuselage.
DE-A-102006053354 disclose an helicopter with radar detectors which are distributed at the fuselage of the aircraft.